1. Managing Environmental Problems and the Urban Microclimate
IB Geography II

2. Objectives
Examine the effects of structures and human activity on urban microclimates, including the urban heat island effect and air pollution.

3. Bell Ringer
“Cities Make Own Weather Due to Trapped Heat” from the National Geographic. Homework article
Use Context Clues to try and define “Urban Heat-Island Effect”
How do cities impact temperature? Find specific evidence that supports your answer.
What trends in temperature can we expect due to increasing urbanization?
How can trees be the solution?

4. Part 1

5. Microclimate
The climate at a very local scale that influences the presence and distribution of organisms is known as the microclimate.
Mesa Verde: vernacular, passive solar, sun angles, thermal mass

6. Structure Of Air Above Urban Area compared to Rural
Greater amounts of dust/pollution particles in air.
There is less water vapor because water is removed quickly by drainage and sewers.
There is less vegetation to take in water and release it later, but more CO2 and higher proportions of toxic fumes due to fuels and discharge of waste gases by industry.

7. Structure Of The Urban Surface
More heat retaining materials with lower albedo (reflectivity).
Tall buildings can be very exposed, and the deep streets are sheltered and shaded.

8. Albedo

9. Urban Heat Island Effect
UHI- describes how urban areas are generally warmer than rural areas.
Urban areas are generally 2-4 degrees warmer than those in the surrounding areas.
Snow in rural areas increases albedo, thereby increasing the differences between urban and rural
Its intensity is the temperature difference between the urban and the rural area.

11. Urban heat profile

12. Impact of Buildings
Tall buildings will give cooler temperatures at street level, as not as much radiation from the sun is able to reach it.
Short buildings will heat up the street level as it allows radiation to be reflected between buildings.
Buildings will also reduce wind speeds (so its warmer) or will channel them (so it’s very windy)

13. Socioeconomic Impacts of the UHI
Human Health: high levels of ozone can cause serious respiratory problems for the elderly, sick, and children.
Human Discomfort: high levels of humidity, atmospheric dust, and poor air quality worsen the quality of life in cities for many
Disease: higher temps increase the likelihood of vector and waterborne diseases in poor cities.

14. Socioeconomic Impacts of the UHI
Energy Waste: high levels of energy used in air conditioning systems are an increasing concern
Heat Stress and Illness: working days are lost and productivity lowered
Environmental Degradation: Intense heat causes the degradation of urban fabric such as rubber and tarmac, creating long-term cost to city governments.

15. Factors Influencing Urban Heat Island Intensity
Weather Conditions: clear and calm with no wind intensify UHI
Topography/hydrology: inland cities far from water have higher UHIs
City population size and density: large population consumes more energy and generates more air pollutants
Level of economic development: developing cities have high density and high energy consumption, but weak emissions controls.

16. Factors Influencing Urban Heat Island Intensity
Building and Street design: narrow streets are cooler by day, but retain heat at night
Land Surface Cover: Concrete and asphalt have a high thermal capacity and absorb solar radiation during the day and release it as heat at night.
Anthropogenic Heating: moving or stationary traffic and air conditioning units increase UHI intensity
Air Pollution: causes heat retention and increases UHI intensity.

17. Partner Pair Share: Questions to Think About
Why does the urban heat island effect matter? Why should we care?
Consider:
Increasing rates of urbanization
Increasing affluence
Possible links to global warming
Positive feedback mechanisms- hotter cities create more heat.

18. Part 2

19. Bell Ringer: Identify and describe TWO differences between urban and surrounding rural areas that contribute to the temperature differences between them.
There is more asphalt, concrete and buildings in urban areas and fewer trees and vegetation.
More trees, factories and machines
Tall buildings and narrow streets in urban areas
More people inhabit urban areas
higher population requires more housing, air conditioning, demand for fossil fuels

20. What Can Be Done about UHI Effect?
Communities can take a number of steps to reduce the urban heat island effect, using four main strategies:
increasing tree and vegetative cover
creating green roofs (also called "rooftop gardens" or "eco-roofs")
using cool or green pavements
installing cool or reflective roofs

21. The Brown Agenda
The Brown Agenda: The stance that the greatest concentration of environmental problems occurs in cities experiencing rapid growth and those that are disproportionately poor
Issues caused by limited availability of land, water and services
Problems such as toxic hazardous waste, pollution of water, air and soil, and industrial accidents.

22. Green Rooftops
A green roof is a roof of a building that is partially or completely covered with vegetation and soil
The term "green roof" may also be used to indicate roofs that utilize some form of "green" technology, such as solar panels
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23. Cool Pavement
The term refers to materials chosen to reduce pavement temperature by increasing pavement reflectivity or controlling temperature by other means through choice of materials and engineering design

24. Construction of Pervious Pavement
Pervious pavements can be made of concrete or asphalt, open-celled stones, and gravel, that are mixed in a manner that creates an open cell structure allowing water and air to pass through.

25. Advantages
Because pervious pavements allow rainwater to seep into the ground through the pavement:
Vegetation is watered, reducing the need for irrigation
Ground water is recharged
Water resources are preserved
Stormwater runoff is reduced
Stormwater runoff quality is improved

26. Question to Think About: Identify and describe TWO actions that local governments in urban areas could take to reduce air pollution.
incentives or taxes
laws or regulations
direct actions like building mass transit, plant vegetation
Education
reduce the number of motor vehicles
improve fuel efficiency
reduce fossil fuel use

27. Part 3

28. Urban Heat waves
A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity
A growing problem due to global warming.
They catch urban societies unprepared and unaware and can result in high mortality rates.
Increasing risk with urbanization and the rapid growth of megacities.

29. Heat Waves
In the United States, heat waves kill more people than all of the so-called “natural disasters” combined. In Chicago, more than 700 people died during one week of 1995.

30. Paris Heat wave of 2003

31. Paris Heat wave of 2003 Close Reading Activity
Questions for Think-Pair-Share
Referring to Figure and 11.31, describe the patterns for day and night-time temperatures (describe general pattern over whole area for both maps and name and locate areas that have temperature anomalies)
Suggest reasons for the patterns you have found. (Hint- use evidence from Keys to help)